TY - JOUR
T1 - An X-Ray Diffraction Study of the Different Nematic Mesophases of Liquid Crystalline Poly(urethane-ester)s
AU - Francescangeli, O.
AU - Yang, B.
AU - LAUS, Michele
AU - Angeloni, A. S.
AU - Galli, G.
AU - Chiellini, E.
PY - 1995
Y1 - 1995
N2 - An x‐ray investigation on powder specimens and stretched oriented fibers of poly(urethaneester)s TDI‐CmCn, derived from various mesogenic alkylene di[4‐(ω‐hydroxyalkyloxy‐4‐oxybenzoyl)oxybenzoate]s (CmCn; m = 2, 4, or 6, and n = 4, 6, 8, or 10) and 2, 4‐toluenediisocyanate (TDI), is reported. Evidence is provided for the formation of two different nematic mesophases in the polymers, namely a cybotactic nematic and a conventional nematic mesophase. Whereas samples TDI‐C2C6, TDI‐C6C4, and TDI‐C6C10 formed one cybotactic nematic mesophase, samples TDI‐C4C6, TDI‐C6C6, and TDI‐C6C8 exhibited both cybotactic nematic and conventional nematic mesophases in a sequence with increasing temperature, which were connected by a first‐order transition. The analysis of the various features of the small‐angle x‐ray diffraction patterns indicates that two structural arrangements, namely smectic C‐like and conventional nematic structures, coexist inside the cybotactic nematic mesophase of these poly(urethane‐ester)s. © 1995 John Wiley & Sons, Inc.
AB - An x‐ray investigation on powder specimens and stretched oriented fibers of poly(urethaneester)s TDI‐CmCn, derived from various mesogenic alkylene di[4‐(ω‐hydroxyalkyloxy‐4‐oxybenzoyl)oxybenzoate]s (CmCn; m = 2, 4, or 6, and n = 4, 6, 8, or 10) and 2, 4‐toluenediisocyanate (TDI), is reported. Evidence is provided for the formation of two different nematic mesophases in the polymers, namely a cybotactic nematic and a conventional nematic mesophase. Whereas samples TDI‐C2C6, TDI‐C6C4, and TDI‐C6C10 formed one cybotactic nematic mesophase, samples TDI‐C4C6, TDI‐C6C6, and TDI‐C6C8 exhibited both cybotactic nematic and conventional nematic mesophases in a sequence with increasing temperature, which were connected by a first‐order transition. The analysis of the various features of the small‐angle x‐ray diffraction patterns indicates that two structural arrangements, namely smectic C‐like and conventional nematic structures, coexist inside the cybotactic nematic mesophase of these poly(urethane‐ester)s. © 1995 John Wiley & Sons, Inc.
UR - https://iris.uniupo.it/handle/11579/3666
M3 - Article
SN - 0887-6266
VL - 33
SP - 699
EP - 705
JO - Journal of Polymer Science, Part B: Polymer Physics
JF - Journal of Polymer Science, Part B: Polymer Physics
ER -